by Susan Davis, USA TODAY

by Susan Davis, USA TODAY

WASHINGTON - Senate Democrats unveiled a $2.7 billion emergency spending bill to address the flow of undocumented children along the U.S. Southwest border, a billion dollars less than President Obama requested.

Senate Appropriations Chairwoman Barbara Mikulski, D-Md., announced the package late Tuesday, saying the legislation will be released Wednesday. Notably absent is a policy change to an existing 2008 law that would make it easier to return the children to their home countries.

Republicans say the policy change is vital for passage, and while the Obama administration has said it could support it, immigration advocates and congressional Democrats oppose it.

Congress has just two weeks to resolve the impasse before they adjourn for the August break. Homeland Security Secretary Jeh Johnson has said critical federal agencies will begin to run out of money by mid-August if Congress does not act. Since October, more than 40,000 children from Guatemala, Honduras and El Salvador have turned themselves in at the border, overwhelming the federal government's resources.

"I believe this bill provides the most effective path forward to meet our nation's obligation to protect the safety and health of the children seeking refuge, speed determination of their asylum status, and create a strategy to go after the smugglers, crime, and violence that are driving children and families from their home countries," Mikulski said in a statement Tuesday. She added that the president's full funding request will ultimately be needed.

House Speaker John Boehner, R-Ohio, has warned that any bill that only provides more money and no new policy will face serious opposition in the House. Republicans have not yet released a bill of their own, but there is broad support among congressional Republicans to change the law to expedite the process to return children home.

Sen. John Cornyn, R-Texas, and Rep. Henry Cuellar, D-Texas, have authored a proposal to streamline how the U.S. processes minors, expediting court proceedings to either allow them to apply for asylum or be returned home. Opponents of the proposal say the border crisis is a humanitarian issue and the U.S. should not rush to remove the children, who may face violence or other threats at home.

Senate Majority Leader Harry Reid, D-Nev., told reporters Tuesday that he does not believe the law needs to be changed because he believes the president has the authority to take executive action. "He has discretion to do a number of different things," Reid said.

Mikluski's bill also includes $615 million to combat wildfires across the country and $225 million to support Israel's "Iron Dome" missile defense system.